What We’ll Do
Presuppositions: The
Projection Problem
Human Communication 1
Lecture 21
Assumptions Hidden in
Language (a)
(1) Jo’s wife just had a baby.
• You could argue that (1) carries no meaning
at all unless Jo has a wife (to convince
yourself of this, negate the sentence and see
what happens).
• So I’m not asserting that Jo has a wife
• Rather, I’m assuming:
•
•
•
•
Observe what Presuppositions are.
Study their effect on communication.
Examine their similarity to pronouns.
Examine their differences from
pronouns.
• We’ll extend the grammar to deal with
them.
• We’ll produce a better account of the
Assumptions Hidden in
Language (b)
• Information that’s conveyed this way is
called a presupposition.
• The words that trigger them are called
presupposition triggers.
– she exists,
– the hearer is happy with this assumption and I’m
opening discussion on her having a baby.
1
Weird Things Presuppositions
Do (a)
Weird Things Presuppositions
Do (b)
• Presuppositions can project from
embeddings.
c. If you don’t like logic, then the course
on pragmatics is really challenging.
d. It’s possible that the course on
pragmatics is really challenging. ･
• Only (2a) implies something is challenging.
• But all the sentences imply there’s a course
on pragmatics.
• Can test if something is a presupposition by
adding not to the sentence and seeing if it’s
still implied.
– If the trigger is syntactically embedded inside not,
it’s possible that, or an if-sentence, it behaves as if
it wasn’t embedded at all: The presupposition is
still implied by the sentence.
(2) a. The course on pragmatics is really
challenging.
b. The course on pragmatics isn’t really
challenging.
Other Presupposition Triggers
• The: The King of France  there is a King of
France.
• Proper Names: Jo  there is someone called
Jo.
• Possessives: John’s children  John has
children  there is someone called John.
• Stop: John stopped smoking  John smoked.
• Realise: John realised X  X.
• Comparatives: Jo is a better linguist than Alex
Alex is a linguist.
More Weird Things
Presuppositions Do
• A presupposition can be cancelled by:
– overtly denying it:
(2) e. The King of France didn’t sign the
proclamation there is no King of France.
– the nature of the context:
(2) f. If Jo has a son, then Jo’s son is bald.
g. If baldness is hereditary, then Jo’s son is
bald. But it’s possible that Jo hasn’t got a son.
2
The Projection Problem (a)
The Projection Problem:
• Suppose a sentence S contains a
presupposition trigger T with
corresponding potential presupposition
P.
• Then how do we compute whether P is
presupposed (and hence implied) by S?
Using Presuppositions in
Communication
To Tony Blair:
• (3) a. Have you broken your promises to the
British People?
• b. When did you realise that the British
People would know that you have broken
your promises to them?
– (3a) doesn’t presuppose anything. No is a good
answer.
– (3b)  Blair realised that the British People would
know...  he broke the promises.
The Projection Problem (b)
• (2) shows that working this out depends on:
– Semantic content of the simple sentences that are
part of S
– Their relation to each other
– Their relation to each other’s presuppositions.
• So in our grammar, you have to look at the
whole DRS built already to see if P survives
as an implication.
Dealing With Presuppositions
in the Grammar
So far:
• The:
NP
x
becomes
DET
the
N
name
x
name(x)
• Reuse a referent if you can. Otherwise,
introduce the referent to the top bit of the box.
3
The Rule in Action
Shortcomings
• the dog can talk about something old or
something new, depending on the
context.
• Examples:
• The dog ran.
• A dog barked. The dog ran.
Rule doesn’t say look for a dog/cat!
• (7) A dog chased a cat. The dog caught
the cat.
x, y
• One DRS is:
Shortcomings Continued
Yet More Shortcomings
• It wont explain the projection from
embeddings:
• (8) If peace is settled, then the King signed
the proclamation.
dog(x) cat(x)
cat(y)
dog(y)
chase(x, y)
catch (y, x)
• We get scope ambiguity where we don’t
want it.
• (9) Every horse jumped the fence.
x, y
king(x)
[peace is settled ] ⇒ proclamation(y)
sign(x, y)
4
Presuppositions Behave like
Pronouns (a)
(10) a. Jack has children and all of Jack’s
children/them are bald.
b. If Jack has children, then all of Jack’s
children/them are bald.
c. Either Jack has no children or all of
Jack’s children/them are bald.
(11) All of Jack’s children/?them are bald.
Presuppositions Behave like
Pronouns (b)
• Presuppositions are like pronouns, but with
semantic content.
– You try and bind it to an antecedent.
– But if you can’t bind it, then there’s enough
semantic content to add it anyway.
• Adding a presupposition to the context is
known as ACCOMODATION.
• You’re assuming that the presupposition is
true, even though you didn’t know it before.
Solution to the Projection
Problem (a)
Solution to the Projection
Problem (b)
1. Replace the presupposition trigger with a
suitable pronoun.
2. If the pronoun has a suitable antecedent (i.e.,
the sentence is acceptable), then the
presupposition doesn’t survive.
3. If the pronoun doesn’t have a suitable
antecedent (i.e., sentence sounds odd), the
presupposition survives.
This gets things right!
• The presupposition is cancelled in (10)
and (2f ) because the pronoun is fine.
• The presupposition survives in (11) and
(2a,b,c,d) because the pronoun is odd.
5
Modelling Presuppositions
Systematically
• The grammar already has mechanisms for
binding pronouns to antecedents.
• So we can use this to handle presuppositions.
• But we must make sure presuppositions bind
in the right circumstances.
• And we must add mechanisms for
accommodation.
– If we’re accommodating a presupposition, then
∗ What do we add?
∗ Where in the DRS do we add it?
Summary (b)
• Presuppositions can be cancelled by
context.
• Presuppositions behave like pronouns
with semantic content:
– You try and bind it to an antecedent;
– But if you can’t, you accommodate it.
• Viewing presuppositions this way can
solve the Projection Problem.
Summary (a)
• There are several devices in language that a
speaker can use to present information as
though the speaker and hearer can both
assume it is true.
• Such information is called a presupposition.
• The things that trigger them are called
presupposition triggers.
• Presuppositions project from embeddings.
Exercises
• 1. If we couldnﾕt accommodate
presuppositions, then just like (12a), (12b)
would be odd, unless there was a preceding
discourse context like (12c) that introduces a
King of France. (12) a. ?He is bald. b. The
King of France is bald. c. There is a King of
France. The King of France is bald. Imagine a
world where you couldnﾕt accommodate
presuppositions. Then what sentences would
you have to precede the following with, in
order to make them acceptable: (13) a. John
didnﾕt stop beating his wife. b. John regretted
that he didnﾕt stop beating his wife. c. Alex
forgot to lock her Alfa Spider again.
6